Sound Devices 302 - Manual (Page 19)

302 User Guide and Technical Information
19
Internal Batteries
The 302 uses a unique battery tube to hold 3-AA batteries. This robust tube is sealed to prevent
potential battery leakage from ruining internal circuitry. The threaded-nickel cap extends beyond the
panel to make battery changes easy and quick.The battery tube extends no farther than adjacent XLR
connectors.
Remove batteries when the unit is stored for extended periods.
External DC Sources
For extended mixer runtime use an external DC source. The 302 can be powered from any DC
source with a voltage range of 5 volts to 18 volts. If using an AC-to-DC transformer, such as a Sound
Devices XL-WPH2, make certain its output voltage falls in the 5–18 V range and can supply at least
4 watts. If an over voltage is applied to the mixer, an internal poly fuse is opened to prevent mixer
damage. The fuse is reset when the voltage is removed.
The external DC supply is isolated (floating) from the circuitry to minimize ground loop and
interaction among devices sharing the same DC source. The external DC connector is a Hirose 4-pin
female. This locking connector mates to Hirose P/N HR10-7P-4P (Sound Devices P/N XL-H). Pin-1
is negative and pin-4 is the positive voltage.
Power Metering
The battery check button indicates battery voltages of internal and external power supplies on
the output meter. The left meter shows the internal battery voltage and the right meter shows
the external battery voltage. Since many different battery types are available for external use, the
external DC metering can be customized for a given battery in the Setup Menu. The power meter
is read from left to right, with the highest voltage indicated with LED’s lit all the way to the left
(green).
Power Consumption
The 302 can vary in the amount of current it draws. Several functions of the 302 directly affect
current draw in different ways. The following list highlights the larger current drawing functions
(listed from highest to lowest current draw).
Microphone
Powering
The main source of current beyond the idle current draw. See Phantom and T-Powering 48
V phantom can draw copious amounts of current out of the batteries depending on what model
microphone is used. Two phantom powered microphones draw twice as much current as one.
Microphones vary widely in their current draw depending on type and phantom voltage applied
Output Drive Level Higher output drive levels into multiple, low-impedance inputs increases current draw
Headphone Output High headphone output levels increase current draw
Meter Brightness
Current draw is slightly increased with higher illumination intensities
Experimentation is recommended to determine battery life for each individual setup and application.